Electrolytic on-site generator

• US 10,400,349 B2
• Filed: 03/08/2016
• Issued: 09/03/2019
• Est. Priority Date: 11/28/2006
• Status: Active Grant

• Current Assignee: De Nora Holdings US, Inc. (Industrie De Nora S.p.A)
• Original Assignee: De Nora Holdings US, Inc. (Industrie De Nora S.p.A)
• Inventors: Stewart, William J., Santillanes, Matthew R., Schwarz, Kevin, Sanchez, Justin, Showalter, Geofrey C., Lee, Kyle
• Primary Examiner(s): Jain, Salil
• Application Number:
  US15/064,385
• Publication Number:
  US 20160186357A1
• Time in Patent Office: 1,274 Days
• CPC Class Codes: C02F 1/006 Water distributors either inside a treatment tank or directing the water to several treatment tanks; Water treatment plants incorporating these distributors, with or without chemical or biological tanks for settling tanks B01D21/24
• CPC Class Codes: C02F 1/008 Control or steering systems not provided for elsewhere in subclass C02F
• CPC Class Codes: C02F 1/4674 with halogen or compound of halogens, e.g. chlorine, bromine
• CPC Class Codes: C02F 2001/46119 Cleaning the electrodes
• CPC Class Codes: C02F 2001/46128 Bipolar electrodes
• CPC Class Codes: C02F 2001/46185 only anodic or acidic water, e.g. for oxidizing or sterilizing
• CPC Class Codes: C02F 2201/007 Modular design
• CPC Class Codes: C02F 2201/4611 Fluid flow
• CPC Class Codes: C02F 2201/4613 Inversing polarity
• CPC Class Codes: C02F 2201/46135 Voltage
• CPC Class Codes: C02F 2201/4614 Current
• CPC Class Codes: C02F 2201/46145 Fluid flow
• CPC Class Codes: C02F 2201/4615 Time
• CPC Class Codes: C02F 2201/4616 Power supply
• CPC Class Codes: C02F 2209/02 Temperature
• CPC Class Codes: C02F 2209/03 Pressure
• CPC Class Codes: C02F 2209/05 Conductivity or salinity
• CPC Class Codes: C02F 2209/42 Liquid level
• CPC Class Codes: C02F 2303/22 Eliminating or preventing deposits, scale removal, scale prevention C02F1/042, C02F1/4602, C02F5/00 take precedence
• CPC Class Codes: C25B 1/14 Alkali metal compounds
• CPC Class Codes: C25B 1/26 : Chlorine; Compounds thereof by simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine C25B1/34
• CPC Class Codes: C25B 11/036 : Bipolar electrodes
• CPC Class Codes: C25B 15/02 : Process control or regulation
• CPC Class Codes: C25B 15/08 : Supplying or removing reactants or electrolytes; Regeneration of electrolytes
• CPC Class Codes: C25B 9/70 : Assemblies comprising two or more cells
• CPC Class Codes: C25F 1/00 : Electrolytic cleaning, degreasing, pickling or descaling

Abstract

Method and apparatus for a low maintenance, high reliability on-site electrolytic generator incorporating automatic cell monitoring for contaminant film buildup, as well as automatically removing or cleaning the contaminant film. This method and apparatus preferably does not require human intervention to clean. For high current density cells, cleaning is preferably performed by reversing the polarity of the electrodes and applying a lower current density to the electrodes, preferably by adjusting the salinity or brine concentration of the electrolyte while keeping the voltage constant. Electrolyte flow preferably comprises water and brine flows which are preferably separately monitored and automatically adjusted. For bipolar cells, flow between modules arranged in parallel is preferably approximately equally distributed between modules and between intermediate electrodes within each module.

Claims

1. A method of cleaning an electrolytic cell, the electrolytic cell comprising:

at least one electrode,

the at least one electrode having an operating electrode polarity and a cleaning electrode polarity that is opposite to the operating electrode polarity, and

the electrolytic cell being operable at an operating current density and being operable at a predetermined cleaning current density that differs from the operating current density;

wherein during operation there is a flow of water into the electrolytic cell and the electrolytic cell operates at the operating current density during operation; and

the method comprising the steps of;

(i) adjusting a salinity, a temperature, or both of an electrolyte of the electrolytic cell until a current density of the electrolytic cell falls to or below the predetermined cleaning current density of the electrolytic cell, the predetermined cleaning current density being 20% or less of the operating current density of the electrolytic cell;

(ii) ceasing the flow of water into the electrolytic cell;

(iii) maintaining a constant voltage to the at least one electrode while the at least one electrode of the electrolytic cell is maintained at the cleaning electrode polarity of the at least one electrode;

(iv) operating the electrolytic cell so as to increase the current density of the electrolytic cell to or above the predetermined cleaning current density; and

(v) starting the flow of water into the electrolytic cell;

repeating a cycle of steps (i)-(v) approximately every 30 seconds or less for a total cleaning time, wherein the total cleaning time is the time to complete cleaning.

2. The method of claim 1 wherein steps (i)-(v) are performed so as to physically dislodge contaminants from the electrolytic cell.

3. The method of claim 1 wherein during operation there is a flow of brine into the electrolytic cell;

and wherein the flow of brine into the electrolytic cell and the flow of water into the electrolytic cell are independently controllable.

4. The method of claim 3 wherein step (i) comprises stopping the flow of brine.

5. The method of claim 1 further comprising increasing the salinity of the electrolyte if the current density does not increase sufficiently during step (iv).

6. The method of claim 1 performed when an amount of oxidant in an oxidant tank is at or below a predetermined low threshold amount and after occurrence of a predetermined event selected from the group consisting of a time period elapsing, exceeding an operation time of the cell, exceeding an amount of electrolyte flow through the cell, and reaching a contamination level.

7. The method of claim 6 further comprising initiating normal operation of the electrolytic cell substantially immediately after the total cleaning time.

8. The method of claim 7 further comprising flushing debris from the electrolytic cell after the total cleaning time.

9. The method of claim 8 wherein the debris comprises scale flakes.

10. The method of claim 1, wherein cleaning is determined to be complete approximately three to five minutes after the first instance of step (i) is started.

11. The method of claim 1 performed approximately once per month.

12. The method of claim 1 wherein the predetermined cleaning current density and the total cleaning time are chosen to expose the electrolytic cell to a predetermined amount of amp-seconds.

13. The method of claim 12 wherein the predetermined amount of amp-seconds is approximately 1800.